feat(session): bound persistence write batching

docs/core-data-structures/persistence.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/persistence.md
-persistence.md: 0968496201defa869d94925e8e5ae3c5da1bbd37
-persistence.zh.md: efb01427b4355e531fb9b86922223cf27d3b3db0
+persistence.md: 3d2bc7ff3b45cd3f38fca0b880a0df9adb928bad
+persistence.zh.md: 035f46d76e0189bd686e991c3d56d486b6f309d5

docs/core-data-structures/persistence.md

@@ -8,7 +8,7 @@ The seam is a textbook [capability seam](../../.agents/notes/implemented/archite
 
 ## The flush checkpoint
 
-`session/event` is a *synchronous* notification; persistence plugins copy the event into a per-session controller and start an eager write without blocking the producer. Concurrent events share the current batch, and events admitted during that write trigger a follow-up batch. `session/flush` waits until no current or pending batch remains, so the loop still uses it as the ordering and error-observation checkpoint before claiming the next ordinary turn. A rejected eager write retains its events; an explicit flush retries them and reports failure through `agent/error` and the logger, never as a session event past the closed turn. Disposal performs the same final drain.
+`session/event` is a *synchronous* notification; persistence plugins copy the event into a per-session controller without blocking the producer. The first pending event starts a fixed batching window, and later events join without resetting its deadline. Expiry starts one durable batch; events admitted during that write receive their own deadline and form a follow-up batch. `session/flush` cancels the wait and drains through quiescence, so the loop still uses it as the ordering and error-observation checkpoint before claiming the next ordinary turn. A rejected background write retains its events and pauses automatic retry; a new event starts a fresh window, while explicit flush retries immediately and reports failure through `agent/error` and the logger, never as a session event past the closed turn. Disposal performs the same final drain. The configured maximum bounds only intentional batching wait, not event-loop scheduling or backend durability latency ([decision](../../.agents/notes/implemented/architecture/2026-08-08-bounded-session-persistence-write-batching.md)).
 
 ## Crash recovery preserves an interrupted turn
 

docs/core-data-structures/persistence.zh.md

@@ -8,7 +8,7 @@
 
 ## flush 检查点
 
-`session/event` 是一个*同步*通知；持久化插件会将事件复制到逐会话控制器，并立即启动写入而不阻塞生产方。并发事件会加入当前批次；在该批次写入期间接纳的事件会触发后续批次。`session/flush` 会等待当前与待处理批次全部清空，因此循环仍将其用作在领取下一个普通轮次之前的顺序与错误观察检查点。立即写入被拒绝时会保留对应事件；显式 flush 会重试这些事件，并通过 `agent/error` 和 logger 报告失败，绝不会把失败记录成已关闭轮次之后的会话事件。dispose（资源释放）会执行同样的最终排空。
+`session/event` 是一个*同步*通知；持久化插件会将事件复制到逐会话控制器，而不阻塞生产方。第一个待处理事件会开启固定批处理窗口，后续事件会加入但不会重置截止时间。窗口到期后会启动一个持久化批次；该次写入期间接纳的事件会获得自己的截止时间，并形成后续批次。`session/flush` 会取消等待并排空至完全停稳，因此循环仍将其用作在领取下一个普通轮次之前的顺序与错误观察检查点。后台写入被拒绝时会保留对应事件并暂停自动重试；新事件会开启新的固定窗口，而显式 flush 会立即重试，并通过 `agent/error` 和 logger 报告失败，绝不会把失败记录成已关闭轮次之后的会话事件。dispose（资源释放）会执行同样的最终排空。配置的最大值只限制有意的批处理等待，不限制事件循环调度或后端完成持久化的延迟（[决策](../../.agents/notes/implemented/architecture/2026-08-08-bounded-session-persistence-write-batching.md)）。
 
 ## 崩溃恢复保留被中断的轮次
 

docs/core-data-structures/session.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/session.md
-session.md: fb04ff3eb3c15d1f3c923ee73d4ba19537d36f11
-session.zh.md: 138159d97a5c368f28821715512632e0ca95b29e
+session.md: 5d54b03df8ec3345e8bf04702f242e3aacf8ec39
+session.zh.md: 5a867cfe302bf02994bfe5a5a704bed55222e8ea

docs/core-data-structures/session.md

@@ -561,7 +561,7 @@ interface TurnEndReasonMap {
 
 ## Execution enclosure and standalone events
 
-A turn encloses one model-loop execution, not the whole session log. AgentLoop records injected `user/message` events only from entering pre-step batches inside a turn; plugin-owned log-only events may still appear between `turn/end` and the next `turn/start`, consuming event seqs without incrementing turn numbers. Persistence eagerly records every contiguous accepted event, while crash repair closes only a genuinely open trailing turn. A producer that needs a durability barrier explicitly awaits `ctx.sessions.flush(session)`.
+A turn encloses one model-loop execution, not the whole session log. AgentLoop records injected `user/message` events only from entering pre-step batches inside a turn; plugin-owned log-only events may still appear between `turn/end` and the next `turn/start`, consuming event seqs without incrementing turn numbers. Persistence admits every contiguous accepted event into a bounded durable batch, while crash repair closes only a genuinely open trailing turn. A producer that needs an immediate durability barrier explicitly awaits `ctx.sessions.flush(session)`.
 
 The optional `dsh-session/invariant` companion enforces the relations owned by core: turn and step numbering, execution-event enclosure, and same-step tool call/result pairing. Merge-extensible event relations belong to the plugin that declares them, so core does not reject an unknown event merely because no turn is open. See [the standalone-event decision](../../.agents/notes/implemented/simplification/2026-07-28-remove-synthetic-log-only-turns.md).
 

docs/core-data-structures/session.zh.md

@@ -565,7 +565,7 @@ interface TurnEndReasonMap {
 
 ## 执行封闭与独立事件
 
-一个轮次包围一次模型循环执行，而不是整个会话日志。AgentLoop 只会从轮次内返回 enter 的 pre-step 批次记录注入的 `user/message` 事件；插件所属的纯日志事件仍可出现在 `turn/end` 与下一个 `turn/start` 之间，占用事件 seq 但不递增轮次编号。持久化会尽快记录每个连续且已接受的事件，而崩溃修复只关闭确实仍处于开放状态的尾部轮次。需要持久性屏障的生产方会显式等待 `ctx.sessions.flush(session)`。
+一个轮次包围一次模型循环执行，而不是整个会话日志。AgentLoop 只会从轮次内返回 enter 的 pre-step 批次记录注入的 `user/message` 事件；插件所属的纯日志事件仍可出现在 `turn/end` 与下一个 `turn/start` 之间，占用事件 seq 但不递增轮次编号。持久化会将每个连续且已接受的事件纳入有界持久化批次，而崩溃修复只关闭确实仍处于开放状态的尾部轮次。需要即时持久性屏障的生产方会显式等待 `ctx.sessions.flush(session)`。
 
 可选的 `dsh-session/invariant` 配套插件会强制核心拥有的关系：轮次与步骤编号、执行事件封闭，以及同一步骤内的工具调用／结果配对。可合并扩展事件的关系由声明它的插件拥有，因此核心不会仅因没有开放轮次就拒绝未知事件。见[独立事件决策](../../.agents/notes/implemented/simplification/2026-07-28-remove-synthetic-log-only-turns.md)。